This invention relates to an oil recovery process employing a fluid containing two or more surfactants, at least one of which is a polyethoxylated alcohol, alkyl phenol, or other alkylaryl compound. More particularly, this invention concerns an oil recovery process suitable for use in oil formations containing water having high salinity and hardness and which additionally may be hotter than about 100.degree. F., so as to avoid phase instability of the surfactant fluid in the higher temperature environment.